I don't know what he can do now about the appalling increase in sentence.
Justify that statement please, specifically the bit emphasised.
He has been convicted or murder (that is a fact).
The minimum sentence for murder in South Africa is 15 years (that is also a fact)
His sentence has been reviewed and he has now received the minimum sentence that is possible for a murder conviction in South Africa of 15 years (he will serve a further 13 years as the sentence takes account of time already served).
In what way is that 'appalling' - don't forget that even now he has received the most lenient sentence possible for the crime that he has been convicted of.